In a SONET (synchronous optical network)/SDH (synchronous digital hierarchy) network which is a synchronous network, in a BLSR (Bi-Directional Line Switched Ring) network defined in GR-1230, there is a restriction that the number of nodes which can be set in one ring is not more than 16, and a configuration so called Ring Inter Connection is used when constructing a network whose node number exceeds 16.
At this time, in order to efficiently utilize a main signal band, an application for relieving a failure over the ring network (ring failure), such as DCP (Drop & Continue on Protection Channel) or DTP (Dual Transmission Protection Channel) or the like, has been used.
When DCP/DTP configuration (RIP (Ring Interconnection Protection)-Enhance) is built, it is necessary to convert provisioning information for the alarm detecting setting of B3 error related to an SS (Service Selector) switching operation and PDI (payload defect indicator)/PLM (payload mismatch)/TIM (trace identifier mismatch) so as to be adapted to a traffic that is to be actually relieved.
DCP/DTP
FIGS. 1A and 1B are diagrams illustrating a DCP operation.
FIGS. 2A and 2B are diagrams illustrating a DTP operation.
In DCP, DTP which is a ring interconnection that is supported by BLSR of 2 fibers or 4 fibers, when BLSR network failure is generated, an SS is automatically provided in a secondary node 2 according to the link where the BLSR network failure is generated. The automatically provided SS is referred to as a relief SS (relieving type SS). There is a case that the relief SS is provided and there is a case that the relief SS is not provided depending on the link where the BLSR network failure is generated (see SS 4 of FIG. 1A, FIG. 2A).
Further, in a DCP, DTP, a normal SS provided in a primary mode 1 is referred to as a regular SS. That is, the different names are used as the situation demands in order to separate with the relief SS. When simply expressed as SS, the SS denotes the regular SS in general (see SS 5 of FIGS. 1A-1B).
In the BLSR network, when ring failure is generated, a protection channel (line) is used for relieving a work line, so that a channel (PCA ch) accessing to a protection line generally ceases the access (case 1).
However in the DCP, DTP, there is a case that relieving of other work channel is not disturbed even when accessing to a protection channel is not ceased, and in such a case, accessing to the protect channel is continued (case 2).
Further, there is a case that a signal bridged to a protection channel by a ring bridge (R-BR) in a switching node is the same as a signal that have been accessed to a protection channel in the secondary node 2 of the original DCP or DTP configuration, and the relief SS 4 is formed in such a case (case 3).
In the DCP, DTP, the secondary node 2 executes any one of the aforementioned cases 1 to 3 depending on a link where a network failure is occurred.
As for the primary node 1 and a terminal node 3, the operation is not changed even when the network failure is occurred anywhere in the ring, and the primary node 1 of the DCP fixes the regular SS 5 at INS (insertion) side. The terminal node 3 of the DTP fixes a DTP-SW 6 at the work side.
The other functions are the same as the normal BLSR functions, and a PCA (Protection Channel Access) cease and a protection channel through are executed, and the switching node executes a ring bridge (R-BR) and a ring switch (R-SW).
Alarm Detection Setting Conversion
FIG. 3 is a diagram illustrating an alarm detection setting convert in the DCP.
In the BLSR, when a ring failure, a failure over a ring network, is occurred, a protection line is used for relieving the work line. In the DCP/DTP configuration, a signal bridged to a protection channel by the ring bridge in the switching node may be the same signal which has been accessed to a protection channel in the secondary node 2 of the original DCP or DTP configuration, and in this case, the relief SS 4 is formed.
When determining a switching operation of the relief SS 4, an alarm detection setting which is a setting of a threshold value or the like for detecting the alarm of B3 (error monitoring of path)/C2 (Path Signal Label)/J1 (path trace) in POH (Path OverHead) of SONET/SDH requires PCA (Protection Channel Access) which has been input in the secondary node 2 before the ring switch is switched as a dedicated setting of another relief SS.
This is apparent by comparing the route before the ring switch is switched illustrated in a solid line and the route at the time when a relief SS is activated after the ring switch is switched illustrated in a chain line as shown in FIG. 3.
That is, this is because that a main signal of a protection channel input in the secondary node 2 at a normal time and a main signal input in the relief SS 4 at a relieving time is absolutely different in content although physical input channels are the same.
In FIG. 3, the PCA (broken line) that is a signal input to East side of the secondary node 2 before the ring switch is switched and a circuit signal (chain line) after the ring switch is switched are different data signals. Accordingly, it is necessary that detection setting of the alarm which is detected as a switching trigger is also respectively set to be appropriate for detection.
The input signal at East side of the secondary node 2 after the ring switch is switched is the same as an input signal of a ring interconnection side of the secondary node 2 before the ring switch is switched. In the secondary node 2, an alarm detection setting 7A at the ring interconnection side may be converted and used as an alarm detection setting 7B at East side after the ring switch is switched.
FIG. 4 is a diagram illustrating an alarm detection setting converted in the DTP. In the diagram, the route before the ring switch is switched is illustrated by a solid line, and the route when the relief SS is activated after the ring switch is switched is illustrated by a chain line.
Also in the case of the DTP configuration, basically similar to the case of the DCP, in the secondary node 2, the input signal at East side after the ring switch is switched is the same as the ring interconnection side input signal before the ring switch is switched. In the secondary node 2, an alarm detection setting 8A at the ring interconnection side may be used as an alarm detection setting 8B at East side after the ring switch is switched.
FIG. 5 is a diagram illustrating a block diagram of an example of a conventional node apparatus. In the diagram, the node apparatus 10 includes interface cards 11-1 to 11-m, 12-1 to 12-m, a work SF (Switch Fabric) 13, and a protection SF (Switch Fabric) 14. The SF's 13, 14 are necessary to provide the circuit by a synchronous transmission signal STS-1 unit, illustrated as STS-SF in diagrams.
A RIP control part 16 provided in the SEs 13, 14, identifies DCP/DTP by soft setting information such as DCP, DTP, or the like and by a RIP (routing information protocol) table in which a span (from primary node to terminal node) passed by each channel is registered and judges whether or not a relief SS is activated.
A RIP conversion part 17 converts a detection setting of B3/C2/J1 alarm in a path alarm detection part 18 by controlling of the RIP control part 16.
Note that an alarm processing technique for eliminating the circuit size of hardware in an ADM device having the BLSR function equipped with a service selector has been known in Japanese Laid-open Patent Publication No. 11-122269.
The speed and the capacity of transmission signal have been increased with recent increase of transmission information quantity. The circuit size has been also increased with the increase. Under the circumstance, the setting space and power consumption of a node apparatus is increased in proportion to the increase of capacity.
In the conventional node apparatus, since the RIP conversion part 17 and the path alarm detection part 18 which are dedicated hardware circuits are provided in the SF's 13, 14 in a concentrated manner, so that it is basically necessary to provide the circuit by a synchronous transmission signal STS-1 unit, and there is a restriction when increasing the processing capacity to the requirement of the increase of capacity.